Carburetor ice is a function of physics, not checklists.
You're faced with two issues when confronted with a checklist calling for carburetor ice. One is the utter lack of defense you'll have if you incur a power loss due to carburetor icing, if you didn't use the carburetor heat. Explain that to your insurance carrier when they seek litigation for damages to to aircraft, passengers, and property on the ground. The other issue is more personal to you; the actual operation of the airplane, your safety, and of course, your legal requirement as pilot in command to ensure the safe outcome of the flight.
First of all, why touch the control if you don't know how to use it, or what it's for? It's there to heat induction air. Why, and by how much?
Without a carburetor air temperature gauge, you have no idea how much heat you're putting into the induction air, let alone the temperature value of air passing through the carburetor venturi. That air must be within a certain range to prevent icing. Too high or too low, and you enter ranges that are either conducive to icing, or that are detrimental to engine operation (particularly at high power settings). Further, by unnecessarily using carburetor heat, you limit available engine power, and substantially alter your fuel-air mixture...which can lead to plug fouling and power loss in some cases. So...before you touch that control, do you have any clue what you're doing, or are you parroting what a low-time instructor told you to do, because that's what he or she was told to do? Worse, are you doing it because you read about it on the internet? Bad form.
What types of carburetor icing are there, and how do they differ? Did anybody ever discuss this with you before advising you when and where to apply carburetor heat?
Carburetor ice, or more accurately induction ice, tends to form in three ways. Two of them occur in the carburetor, and one of them doesn't (and can't be affected by carburetor heat). Induction ice at the air intake (typically around the air filter) occurs when flying in freezing conditions and visible moisture, and can't be removed by carburetor heat. It can only be prevented by not entering conditions that cause such icing.
Carburetor icing, inside the carburetor, however, is more insidious, and occurs on warm summer days well outside of visible moisture. It occurs in two ways; at or close to idle, and with an open throttle. Too often students are mislead to believe that carburetor icing is a product of operating at low power settings, when this is patently untrue.
Your carburetor has two fuel jets, or inlets, which provide fuel to air flowing through the carburetor, and give your engine life. One is an idle jet, which serves the carburetor only when the throttle plate is closed. The engine, acting as a heavy vacuum cleaner or suction machine, draws air through the air filter and carburetor. When the throttle plate is closed, this is the same as placing one's hand over the hose on a vacuum cleaner; the pressure in the hose drops, and the machine (engine) sucks away at your hand...or in this case, the closed throttle plate.
Some air gets past the throttle plate, and this happens at a point where a controlled leak is allowed...this is precisely where the idle jet is placed, and also where carb icing occurs at idle. Block that small controlled leak at idle, and one cuts off the airflow to the engine. Cut off the airflow and one cuts off the pressure drop in that same location that draws fuel into the airstream, and subsequently the engine quits from lack of airflow and lack of fuel. Opening the throttle makes this problem go away; the carburetor isn't choked off from icing...just the edge by the idle jet. Carburetor heat prevents this icing in the first place.
During a prolonged descent with idle power, the engine cools, and carburetor heat becomes less effective. Carburetor heat in most light piston powered airplanes is little more than a small door in a box ahead of the carburetor which is moved to allow air from inside the cowling to be drawn into the carburetor. This air is warmer than ambient air outside the cowling. How warm this air is largely depends on things such as the position of cowl flaps (where installed), the airspeed and airflow of the nacelle (how fast it's receiving cooling air, and how much), and the power setting of the engine. An engine operating at a high power setting is hotter than an engine at idle, and makes for hotter air inside the cowl. Closed cowl flaps make for hotter air than open ones, and so forth.
One must realize that in a small piston engine installation without a carburetor air temperature gauge, one is taking a shotgun approach to removing or preventing icing. One has no idea where in the carb temp range one is placing the carb air temp, when applying carburetor heat. It's what one might call a swag, or scientific wild-assed guess...hardly appropriate in the artistic science we call flying, but often all one has when attempting to control carburetor icing.
Most airplanes don't come with an ice detector, either, so one has no way of knowing if one has ice, or has removed ice, unless one understands the formation of icing, it's removal, and how to tell the difference by power response, vibration, and sound.
The other kind of carburetor icing occurs with an open throttle, which may be partial, or wide-open throttle (WOT); it can occur at high power settings in cruise or on takeoff...or on the go-around.
Both kinds of carburetor ice form as a result of a drop in pressure and temperature at the carburetor venturi, or by the calibrated leak at the idle jet with a closed throttle. Pilots are often mistakenly taught that carburetor icing only occurs at low power settings, when in fact a high power setting produces the greatest airflow and temperature drop, and can produce the fastest power loss. Think about it. This occurs at wide open throttle or partial throttle...such as a takeoff or go-around. Given some of the comments about the lack of training that's provided, I have to wonder how many have considered the possibility or likelihood of carb icing during those critical phases of flight.
Don't be lulled into thinking that the only times to apply carburetor heat are when one is approaching to land. Carburetor heat, like the mixture control, is there to be used. One does not need to rope one's self into a constraining and artificial mental limit of thinking that one cannot use it liberally as required. One can, and must. I've seen pilots land shaken and unsure about the engine failure they just experienced...when in fact they just lost power due to carburetor icing...and had absolutely no idea. I've seen them look astounded when a short time later we were able to start their airplane and run it normally...they were absolutely convinced that carburetor icing couldn't have happened to them...after all, they were at a high power setting on a hot day. Carburetor ice? Naw...can't be.
It is.
When one has been using carburetor heat during a prolonged descent and approach, and one pushes it in at the moment of go-around, one may suddenly develop carb ice, and get a rough engine. Or one may already have carburetor ice, shed some of it off the throttle plate as the throttle is advanced, and get a rough engine. Or one may see no response at all. Knowing which is which, and what to expect, may make the difference between abandoning the go-around and landing on the remaining runway, the re-application of carburetor heat, or even an unnecessary execution of a forced landing off-field.
If one has been using carburetor heat during the approach, especially without a mixture change, one may have significantly enriched the mixture. With 100LL fuel, which contrary to the name does contain a high concentration of tetraethyl lead, spark plug fouling is a distinct possibility. If one has flown a prolonged descent with carburetor heat and no leaning, one may push the power up and find a rough engine that can't be cleared with additional carburetor heat...because the spark plugs are fouled. I've seen student after student, and instructor after instructor, bring me an airplane repeatedly throughout a single day, with reports of a rough engine. Upon pulling lower spark plugs, I have found completely shorted spark plugs, glazed over with lead and carbon deposits, which must be chipped free using a pick, and the spark plug thoroughly cleaned before being returned to service. The problem wasn't the magneto gap, it wasn't the spark plug, and it wasn't a timing issue...it was a pilot issue and a failure to properly lean, and too much unnecessary use of carburetor heat.
Rather than teach rote use of the carb heat control, one should be teaching proper use, as well as the principles of it's application, and the principles of carburetor function. To fail to do so borders on criminal behavior, and is highly inappropriate.